The purpose of this project is to study how sensorineural hearing loss affects the ability of listeners to discriminate between complex sounds on the basis of spectral shape. The capability for distinguishing between complex auditory signals, including both speech and nonspeech sounds, is facilitated by a process known as "auditory profile analysis". According to preliminary theory, auditory profile analysis involves a spectral comparison or template matching between a given sound input and a reference stimulus stored in long-term memory. Frequency selectivity, stimulus uncertainty, auditory perceptual learning and short-term and long-term auditory memory appear to be important in auditory profile analysis. A two-interval forced-choice psychophysical measurement technique, in which each stimulus presentation level is chosen at random, allows the measurement of discriminability based solely on spectral shape. While the importance of auditory profile analysis in the discrimination of complex sounds is clear, virtually nothing is known about its actions in the presence of sensorineural hearing loss. The specific objectives of the present study are to refine the theory of auditory profile analysis through comparative measures between normally hearing and hearing-impaired listeners, and to advance the understanding of the perception of complex auditory stimuli in impaired listeners.